Elemental sulphur or modified sulphur can be used to bind aggregate and filler, thereby providing sulphur cement products such as sulphur mortar and sulphur concrete. Sulphur concrete can be used in a variety of pre-cast concrete applications such as marine defences, paving slabs, road barriers and retaining walls.
Sand is very commonly used as a fine aggregate in sulphur mortar and sulphur concrete. It is desirable to use sand that is available locally for reasons of cost and convenience.
U.S. Pat. No. 4,376,830 discusses the problem of using aggregates that are contaminated with water-expandable clays. These clays can cause the sulphur mortar or concrete to disintegrate when exposed to water. It is possible to remove the clays by washing procedures, but this is uneconomical. The '830 patent teaches that organosilanes having functional groups such as amino, epoxy and mercapto groups can be incorporated into sulphur mortar or concrete to reduce the water expandability of the water-expandable clay.
The present inventors have found that sulphur mortar and sulphur concrete prepared from porous sand having a high surface area is also liable to disintegrate when exposed to water. This is not due to the presence of expandable clays (washing procedures do not affect the water stability of sulphur mortar and sulphur concrete prepared from the sand). The inventors have sought to improve the water stability of sulphur mortar and sulphur concrete prepared from this high-surface-area sand.